Magnetic sensor devices are utilized to, for example, convert patterns printed with magnetic inks that are applied on a medium requiring a high-level security, such as a paper bill or a personalized check, into electronic information, and to determine the authenticity of the medium based on such information. In the case of devices like automatic vending machines and ticket vending machines which handle a small amount of money and therefore are required to be low in cost, two to five magnetic detection elements like Hall elements are used in a magnetic-pattern reading unit to detect magnetic information on multiple stripe-shape lines in the feeding direction of the medium (paper bill), thereby detecting the medium, determining the kind, and examining the authenticity. According to such magnetic sensor devices, since only specific locations of the magnetic patterns are readable, when the kind of the target medium (magnetic pattern to be determined) changes, it is required to change the reading unit.
Conversely, in the case of magnetic sensor devices applied to bill returning type ATMs (Automated Teller Machines), business-purpose bill counters or bill sorters which require a high-level bill authenticity examination, a large number of magnetic detection elements over the whole width of a paper bill or a personal check are disposed in a bill processing unit, and thus more pieces of magnetic information can be utilized for the determination and authenticity examination.
Patent Literature 1 discloses a magnetic body detection device that includes, for example, a magnetic resistance sensor disposed at the middle of the moving route of a magnetic body, a lower magnet which has the S and N polarities oriented along the movement direction of the magnetic body, and an upper magnet which has the N and S polarities oriented along the movement direction of the magnetic body. The lower magnet and the upper magnet are disposed so as to have, via the moving route of the magnetic body therebetween, the S polarity of the lower magnet and the N polarity of the upper magnet facing with each other, and have the N polarity of the lower magnet and the S polarity of the upper magnet facing with each other.
According to the magnetic image sensor disclosed in Patent Literature 1, multiple magnetic resistance sensors are disposed linearly. Output signals by the respective magnetic resistance sensors are supplied to the processing circuit simultaneously or time sequentially, and are stored in the processing circuit as one-dimensional image signals. Such a reading operation is performed every time the magnetic body moves by a predetermined pitch, thereby obtaining a two-dimensional magnetic pattern image.
Patent Literature 1 discloses that the output signals from the multiple magnetic resistance sensors are converted into digital values through an A-D converter to execute a signal processing. In this case, since the sampling is performed on the output signals, the resultant information is discrete in time.